The invention relates to a shoe structure, which is at least part of a shoe and comprising: an upper, comprising at least one outer layer and a lining, which lines the inside of the outer layer and includes a waterproof and water-vapor permeable layer; an insole connected to the lower end area of the outer layer; and a sole.
Shoes which have a shoe structure with a lining that includes a waterproof and water-vapor permeable functional layer, are well known for their wearing comfort. It is, however, often difficult to guarantee waterproofing in this kind of shoe because, for example, every seam which is sewn into the lining can transport water to the inside of the shoe by capillary action. For this reason, the lining that includes a waterproof, water-vapor permeable functional layer is often constructed in the shape of a sock (better known as a booty), which is only connected to the outer layer at the upper opening of the shoe. In this case, the seams or other types of connection required for formation of the sock can be easily sealed with a waterproof adhesive tape, so that the sock design of the lining guarantees that the shoe is waterproof. However, using the sock design dictates that there must also be lining in the area of the sole, in order to seal the inner area hermetically against water, despite the fact that it is often unimportant whether or not the lining is water-vapor permeable in the sole area, because the sole material itself is not water-vapor permeable. For this reason, the expense involved in constructing the lining in the form of a sock (booty) is often too high for many purposes.
For this reason, a method has been used, for example in accordance with DE-A-38 21 602, in which a porous strip is inserted in shoes with an injection-molded sole, in order to connect the outer layer and the lining. During the injection moulding process, the material of the sole penetrates this porous strip right through to the lining, so that the seam which joins the porous strip to the lining is surrounded by the sole material. This embodiment cannot be used for certain types of shoe, for example shoes with a flex design. In shoes with flex construction, the lower area of the outer layer is turned back to the outside of the shoe so that this lower end area of the outer layer is at least approximately parallel to the outsole and sewn to the insole. In this case, the extreme edge of the turned-back end area of the outer layer and the extreme edge of the sole have the same contour. In order to guarantee that the shoe is waterproof, these types of shoe are still made using the more expensive "sock" construction method.